Chickens sold in supermarkets need to test at 100 percent chicken DNA. The standard, however, is lowered when it comes to meat that has been marinated, seasoned or prepared such as those sold in food chains so they may have lower chicken DNA percentage.

Less Than 50 Percent Chicken DNA

Chicken meat from most of the fast food chains had scores from 85 to 90 percent chicken DNA except Subway, which showed far lower percentage for chicken DNA.

Soy

What's in Subway's chicken meat? DNA tests revealed it is soy but Subway Canada said in a statement that they cannot confirm the veracity of the lab tests' results. The company said that its oven roasted chicken and chicken strips contain only 1 percent or less of soy protein, which it uses to stabilize mixture and texture.

The company added that all of the chicken items it offers are 100 percent white meat chicken that has been marinated, oven-roasted and grilled.

"We tested our chicken products recently for nutritional and quality attributes and found it met our food quality standards," Subway said adding that it will look into the matter with its supplier to ascertain that the chicken it offers to customers meet the highest standards it has set for all of its ingredients and menu items.

Restructured Products

University of Guelph food scientist Ben Bohrer said he does not know how the products that the Marketplace investigation tested were made but he explained what is known as restructured products in the fast food industry.

Restructured products are in essence ground meat or smaller pieces of meat that were bound together with other ingredients so they would last longer, taste better, and even cost cheaper.

Human And Rat DNA In Hamburgers

The findings from the Marketplace investigation may be surprising but earlier analyses of food products have revealed an array of DNA that most people do not expect to be present in their food.

Last year, California upstart Clear Labs used a molecular analysis technique to test hamburgers and found rat DNA in three samples. It also found human DNA in a frozen vegetarian burger. While these DNA traces may speak something about the quality of the meat products, the report said that these do not pose immediate risk to consumer health.

"In general, the presence of human and rat DNA is a potential indicator of low quality and speaks to issues of inconsistent adherence to handling protocols," Clear Labs said. "While we don't consider it a public health concern, it also creates the potential risk for that product to become an outlier as the industry shifts towards greater transparency and more stringent quality standards."